View Full Version : Dammit. Cam chain lock nut

03-26-2013, 3:17 PM
Putting the xs650 engine back together and can't find the damn lock nut for the can chain tensioner. Anybody know what size it is? Wonder if I'll have luck finding something thatll work at the hardware store. Just usually something that size is also pretty thick and I may not be able to fit the cover over it.

03-26-2013, 5:37 PM
Which nut are you meaning? My guess is #18 pictured below but not really sure...


03-26-2013, 5:41 PM

03-26-2013, 5:43 PM
To be honest. I don't even remember taking it off. I'm wondering if it was ever on there at all since I've owned it.

03-26-2013, 5:48 PM
I would carry #15 in there and find one that fits...easiest way I know of.

03-26-2013, 6:00 PM
Yeah that's what I'm gonna have to do and hope it fits in there. The walls are a little tight. I could always grind down whatever nut I find that works if needed. Man that'll be a pain.

03-26-2013, 6:10 PM
Then you carry #18 too...screw "NEW #16" on #15 a little and if it slides into #18 which is a sort of gauge for that hole size...you're golden.

Make sure to leave #18's o-ring home so you don't lose it.

03-26-2013, 6:13 PM

Thanks dude. Sometimes you need another person to point out the obvious. :o

03-26-2013, 7:21 PM
No worries sometimes the solution is apparent but not exactly obvious. ;)

04-01-2013, 6:08 AM
Turns out from 76 to 78 they didnt use a lock nut. Before 76 and after 78 they did. Yamaha must have realized the error in their ways.

04-01-2013, 8:37 AM
With the exception of type A and type B commonly found on the earliest XS's, there's no mechanical advantage in one style over the other.


04-01-2013, 10:51 AM
Yeah I've got type d. Ok, I thought I was missing it till I researched more.

04-02-2013, 2:15 PM
Yeah I've got type d. Ok, I thought I was missing it till I researched more.

Good, I had been wondering if it'd fallen somewhere inside the engine,,,,

04-02-2013, 7:51 PM
Gotta love it when they can't make up their mind on a part and keep reinventing the wheel... especially when none work better than any of the previous.

It appears the lock nut model has an O-ring behind it, then the cap nut seats onto the lock nut with an O-ring. I am glad that mystery got solved.

04-03-2013, 5:14 AM
And also thanks for that pic blackbetty. It doesn't get any clearer than that. I feel better now. Thought I was going crazy not remembering taking a lock nut off.